It could mean one of so many different things. Investigators for law enforcement do look at social media for postings, friends lists and a variety of other things. I cannot tell you what it means only that if you are doing the right thing your chances of having difficulties goes down.
There is nothing to prevent anyone to view your social media profiles. There are many reasons a prosecutor may be looking up your case/profile. It is possible they have a similar case and wish to review the record, analyze the facts, and see your conduct post conviction, etc. You can not be re-prosecuted for the same crime and cannot be violated since it has been many years. You can block this person from Facebook or change your security level so only friends can view your profile.
People always want to see a comeback story. People always rubberneck a major collision. Humans are deeply conflicted beings. Sure, people that were interested in your case want to see how you turn out. It's uplifting if someone with a troubled past can make it. It confirms deep inner pessimism if a tiger does change its stripes, and then you would serve as a cautionary lesson of "I told you so." This grand world is completely interdependent. You hold the future in your hands. And your future is our future.
It means you are being stalked, err investigated, by a prosecutor. It appears someone has complained about you or someone with a similar name. I suggest contacting an attorney who at the very least can make contact to the person reviewing you sights for the purpose of providing clarification. Many reputable attorneys offer a free consultation. I suggest meeting with at least one soon while the stalking is still fresh.
If you need further analysis of the situation, our firm is very good with digital evidence as mentioned in several recent news stories on ABC and their affiliates. See the media tags on my website.
The response above is not intended as legal advice since it’s impracticable to provide thorough, accurate advice based upon the query without additional details. It is highly recommended that one should seek advice from a criminal defense attorney licensed in your jurisdiction by setting up a confidential meeting. Moreover, this response does not constitute the creation of an attorney-client relationship since this message is not a confidential communication because it was posted on a public website, thereby publicly disclosing the information, which is another reason to setup a confidential meeting with an attorney.
Unfortunately you can't prevent the snoopers from snooping. I take it as a given that all our Internet communications - Facebook, linkedin, chat rooms, and even email - are being monitored by government agents. Do you really think that federal agents - FBI, CIA, NSA - can't know everything about you in the virtual world? The IRS just announced it doesn't need a warrant to read your email: http://m.washingtontimes.com/news/2013/apr/11/irs-taxpayers-we-dont-need-no-stinkin-warrant/
The point is you have to assume there is no privacy left in this brave new world of post 9/11 government surveillance. In all likelihood the man has bigger fish to fry than you but I'd watch your back (as apparently you are already). Best of luck